Backpack



FIG. 1 is a front view of a backpack showing my new design according to a first embodiment;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a front perspective view thereof;

FIG. 5 is a rear perspective view thereof;

FIG. 6 is a front view of a backpack showing my new design according to a second embodiment;

FIG. 7 is a right side view thereof;

FIG. 8 is a left side view thereof;

FIG. 9 is a front perspective view thereof; and,

FIG. 10 is a rear perspective view thereof.

The dashed broken lines in the drawings illustrate portions of the backpack that form no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 